Low-rigidity workpiece machining assistance system

ABSTRACT

A machining assistance system for assisting a machining apparatus includes: a workpiece supporting force generating unit, which generates workpiece supporting force against machining reaction force that is exerted on a machining portion of a workpiece by a working tool; a supporting device, which moves the supporting force generating unit while supporting the supporting force generating unit; and a workpiece supporting force control device, which controls operation of the workpiece supporting force generating unit and operation of the supporting device based on machining reaction force related data related to the machining reaction force and machining position related data related to a machining position of the working tool, such that the workpiece supporting force generating unit exerts the workpiece supporting force on the workpiece against the machining reaction force.

TECHNICAL FIELD

The present invention relates to a machining assistance system, andparticularly to a machining assistance system for assisting in machininga low-rigidity workpiece, such as a thin plate or a thin-wall cylinder.

BACKGROUND ART

Generally in machining work, a machine tool is used in the machining, inwhich a workpiece, i.e., a machining target object, and a working toolare moved (i.e., rotated or linearly moved) relative to each other, andthe workpiece is machined into an intended shape. In recent years, NCmachine tools, the machining by which is automated by numerical control,are mainly used.

Recently, various technologies for assisting in the machining have beendeveloped. For example, there is a disclosed system for removingremaining chips after machining by a machining center (see PatentLiterature 1, for example).

CITATION LIST Patent Literature

PTL 1: Japanese Laid-Open Patent Application Publication No. H10-118884

SUMMARY OF INVENTION Technical Problem

In the case of machining a low-rigidity workpiece such as a thin plateor a thin-wall cylinder, a cutting error or the like tends to occur,which is due to vibration, deformation, etc., of the workpiece caused bymachining reaction force. Therefore, it is conceivable to take ameasure, for example, reducing cutting conditions such as the amount ofcutting and the feed speed, or cutting-to-zero, i.e., cutting the sameportion twice. However, adopting such a method causes a reduction inmachining efficiency.

The present invention has been made to solve the above-describedproblems. An object of the present invention is, in machining alow-rigidity workpiece, to prevent a reduction in machining precisiondue to deformation of the workpiece while suppressing a reduction inproduction efficiency.

Solution to Problem

In order to solve the above-described problems, a machining assistancesystem according to one aspect of the present invention is a system forassisting a machining apparatus, the machining apparatus including: aworkpiece retaining tool that retains a workpiece; a machining unit thatmachines the workpiece retained by the workpiece retaining tool bydriving a working tool; and a machining control device that performscontrol of moving the machining unit relative to the workpiece retainingtool to position the working tool at a machining position. The machiningassistance system includes: a workpiece supporting force generating unitthat generates workpiece supporting force against machining reactionforce that is exerted on a machining portion of the workpiece by theworking tool; a supporting device that moves the supporting forcegenerating unit while supporting the supporting force generating unit;and a workpiece supporting force control device that controls operationof the workpiece supporting force generating unit and operation of thesupporting device based on machining reaction force related data relatedto the machining reaction force and machining position related datarelated to the machining position of the working tool, such that theworkpiece supporting force generating unit exerts the workpiecesupporting force on the workpiece against the machining reaction force.

According to the above-described configuration, the workpiece supportingforce generating unit generates workpiece supporting force againstmachining reaction force that is exerted on the machining portion of theworkpiece by the working tool, and the supporting device moves thesupporting force generating unit while supporting the supporting forcegenerating unit. The workpiece supporting force control device controlsthe operation of the workpiece supporting force generating unit and theoperation of the supporting device based on the machining reaction forcerelated data and the machining position related data, such that theworkpiece supporting force generating unit exerts the workpiecesupporting force on the workpiece against the machining reaction force.Accordingly, by controlling the workpiece supporting force tosubstantially match the machining reaction force, even if the workpieceis a low-rigidity workpiece, deformation of the workpiece due to themachining reaction force can be prevented. Consequently, a reduction inmachining precision due to deformation of the workpiece can beprevented. Since it is not necessary to, for example, reduce themachining conditions, a reduction in production efficiency can besuppressed.

The machining reaction force herein means force that is exerted from theworking tool to the workpiece at the time of machining. For example, inthe case of cutting work, cutting resistance is exerted from theworkpiece to the working tool. In this case, reaction force against thecutting resistance, the reaction force being exerted from the workingtool to the workpiece, is the machining reaction force (cutting reactionforce).

The machining unit may be configured to perform machining of theworkpiece retained by the workpiece retaining tool by causing a columnaror discoid rotating tool with a cutting edge or grinding stone formed onits peripheral surface or distal end surface to rotate about a centralaxis of the rotating tool. The workpiece supporting force generatingunit may include a columnar rotary body and a rotation driver thatcauses the rotary body to rotate about a central axis of the rotarybody. The workpiece supporting force control device may be configuredto, based on the machining reaction force related data and the machiningposition related data and by using the supporting device, perform:control of an orientation and a position of the workpiece supportingforce generating unit, such that the central axis of the rotary body isparallel to the central axis of the rotating tool, and the rotary bodyexerts pushing force on the workpiece against cutting reaction forcethat is exerted on the workpiece by the rotating tool; and control ofoperation of the rotation driver to cause the rotary body to rotate,such that a rotational torque is exerted on the workpiece against atorque that is generated by the cutting reaction force. The machiningherein includes cutting and grinding.

According to the above configuration, in the case where the machiningapparatus is an apparatus for performing machining of the workpiece bythe rotating tool, based on the machining reaction force related dataand the machining position related data and by using the supportingdevice, the workpiece supporting force control device performs: controlof the orientation and the position of the workpiece supporting forcegenerating unit, such that the central axis of the rotary body isparallel to the central axis of the rotating tool, and the rotary bodyexerts pushing force on the workpiece against cutting reaction forcethat is exerted on the workpiece by the rotating tool; and control ofthe operation of the rotation driver to cause the rotary body to rotate,such that a rotational torque is exerted on the workpiece against atorque that is generated by the cutting reaction force. Therefore, inthe case where the machining apparatus is an apparatus for performingmachining of the workpiece by the rotating tool, even if the workpieceis a low-rigidity workpiece, a reduction in machining precision due todeformation of the workpiece can be prevented while suppressing areduction in production efficiency.

(Side Surface Cutting: End Mill)

The machining unit may be configured to perform cutting of a sidesurface of the workpiece retained by the workpiece retaining tool bycausing a columnar rotating cutting tool with a cutting edge formed onits peripheral surface to rotate about a central axis of the rotatingcutting tool, and the workpiece supporting force control device may beconfigured to, based on the machining reaction force related data andthe machining position related data and by using the supporting device,perform: control of the orientation and the position of the workpiecesupporting force generating unit, such that the central axis of therotary body is parallel to the central axis of the rotating cuttingtool, a peripheral surface of the rotary body faces the peripheralsurface of the rotating cutting tool with the workpiece positioned inbetween, and the peripheral surface of the rotary body exerts pushingforce on the workpiece against cutting reaction force that is exerted onthe workpiece by the rotating cutting tool; and control of operation ofthe rotation driver to cause the rotary body to rotate in the samedirection as a rotation direction of the rotating cutting tool, suchthat a rotational torque is exerted on the workpiece against a torquethat is generated by the cutting reaction force.

According to the above configuration, in the case where the machiningapparatus is an apparatus for performing cutting of a side surface ofthe workpiece by the rotating cutting tool, based on the machiningreaction force related data and the machining position related data andby using the supporting device, the workpiece supporting force controldevice performs: control of the orientation and the position of theworkpiece supporting force generating unit, such that the central axisof the rotary body is parallel to the central axis of the rotatingcutting tool, the peripheral surface of the rotary body faces theperipheral surface of the rotating cutting tool with the workpiecepositioned in between, and the peripheral surface of the rotary bodyexerts pushing force on the workpiece against cutting reaction forcethat is exerted on the workpiece by the rotating cutting tool; andcontrol of the operation of the rotation driver to cause the rotary bodyto rotate in the same direction as the rotation direction of therotating cutting tool, such that a rotational torque is exerted on theworkpiece against a torque that is generated by the cutting reactionforce. Therefore, in the case where the machining apparatus is anapparatus for performing cutting of a side surface of the workpiece bythe rotating cutting tool, even if the workpiece is a low-rigidityworkpiece, a reduction in machining precision due to deformation of theworkpiece can be prevented while suppressing a reduction in productionefficiency.

(Front Surface Cutting: Milling, Hole Machining: Drilling)

The machining unit may be configured to perform cutting of a surface ofthe workpiece retained by the workpiece retaining tool by causing acolumnar rotating cutting tool with a cutting edge formed on its distalend surface to rotate about a central axis of the rotating cutting tool,and the workpiece supporting force control device may be configured to,based on the machining reaction force related data and the machiningposition related data and by using the supporting device, perform:control of the orientation and the position of the workpiece supportingforce generating unit, such that the central axis of the rotary body isparallel to the central axis of the rotating cutting tool, a distal endsurface of the rotary body faces the distal end surface of the rotatingcutting tool with the workpiece positioned in between, and the distalend surface of the rotary body exerts pushing force on the workpieceagainst cutting reaction force that is exerted on the workpiece by therotating cutting tool; and control of operation of the rotation driverto cause the rotary body to rotate in a direction reverse to a rotationdirection of the rotating cutting tool, such that a rotational torque isexerted on the workpiece against a torque that is generated by thecutting reaction force.

According to the above-described configuration, in the case where themachining apparatus is an apparatus for performing milling or holemachining on a surface of the workpiece by the rotating cutting tool,based on the machining reaction force related data and the machiningposition related data and by using the supporting device, the workpiecesupporting force control device performs: control of the orientation andthe position of the workpiece supporting force generating unit, suchthat the central axis of the rotary body is parallel to the central axisof the rotating cutting tool, the distal end surface of the rotary bodyfaces the distal end surface of the rotating cutting tool with theworkpiece positioned in between, and the distal end surface of therotary body exerts pushing force on the workpiece against cuttingreaction force that is exerted on the workpiece by the rotating cuttingtool; and control of the operation of the rotation driver to cause therotary body to rotate in the direction reverse to the rotation directionof the rotating cutting tool, such that a rotational torque is exertedon the workpiece against a torque that is generated by the cuttingreaction force. Therefore, in the case where the machining apparatus isan apparatus for performing milling or hole machining on a surface ofthe workpiece by the rotating cutting tool, even if the workpiece is alow-rigidity workpiece, a reduction in machining precision due todeformation of the workpiece can be prevented while suppressing areduction in production efficiency.

(Grinding)

The machining unit may be configured to perform grinding of a sidesurface of the workpiece retained by the workpiece retaining tool bycausing a discoid rotating grinding tool with grinding stone formed onits peripheral surface to rotate about a central axis of the rotatinggrinding tool, and the workpiece supporting force control device may beconfigured to, based on the machining reaction force related data andthe machining position related data and by using the supporting device,perform: control of the orientation and the position of the workpiecesupporting force generating unit, such that the central axis of therotary body is parallel to the central axis of the rotating grindingtool, and the rotary body exerts pushing force on the workpiece againstgrinding reaction force that is exerted on the workpiece by the rotatinggrinding tool; and control of operation of the rotation driver to causethe rotary body to rotate, such that a rotational torque is exerted onthe workpiece against a torque that is generated by the grindingreaction force.

According to the above configuration, in the case where the machiningapparatus is an apparatus for performing grinding of a side surface ofthe workpiece by the rotating grinding stone, based on the machiningreaction force related data and the machining position related data andby using the supporting device, the workpiece supporting force controldevice performs: control the orientation and the position of theworkpiece supporting force generating unit, such that the central axisof the rotary body is parallel to the central axis of the rotatinggrinding tool, and the rotary body exerts pushing force on the workpieceagainst grinding reaction force that is exerted on the workpiece by therotating grinding tool; and control of the operation of the rotationdriver to cause the rotary body to rotate, such that a rotational torqueis exerted on the workpiece against a torque that is generated by thegrinding reaction force. Therefore, in the case where the machiningapparatus is an apparatus for performing grinding of a side surface ofthe workpiece by the rotating grinding stone, even if the workpiece is alow-rigidity workpiece, a reduction in machining precision due todeformation of the workpiece can be prevented while suppressing areduction in production efficiency.

The machining assistance system may further include a dynamometer thatdetects motive power exerted on the workpiece, and the machiningreaction force related data may be the motive power detected by thedynamometer.

According to the above configuration, the motive power exerted on theworkpiece during the machining is directly detected in real time by thedynamometer. This makes it possible to perform accurate feedback controlof the workpiece supporting force by using the motive power detected bythe dynamometer. For example, in the case of cutting work, the motivepower exerted on the workpiece is detected by the dynamometer, andfeedback control of the workpiece supporting force is performed, suchthat the value of the detected motive power is kept to zero.

The machining unit may include the working tool and a motor that drivesthe working tool. The machining assistance system may further include acurrent sensor that detects an electric current flowing through themotor. The machining reaction force related data may be a current valueof the electric current flowing through the motor, the electric currentbeing detected by the current sensor.

According to the above configuration, the current value of the motordriving the working tool is a value corresponding to the machiningreaction force. Accordingly, the machining reaction force exerted on theworkpiece during the machining is indirectly detected in real time bythe current sensor. This makes it possible to perform feedforwardcontrol of the workpiece supporting force by using the motor currentvalue detected by the current sensor.

The machining assistance system may further include a vibration meterthat is provided on the workpiece retaining tool and that measuresvibration of the workpiece retained by the workpiece retaining tool, andthe machining reaction force related data may be the vibration measuredby the vibration meter.

According to the above configuration, the vibration of the workpiececorresponds to the machining reaction force exerted on the workpiece.Accordingly, the machining reaction force exerted on the workpieceduring the machining is indirectly measured in real time by thevibration meter. This makes it possible to perform feedback control ofthe workpiece supporting force by using the vibration measured by thevibration meter. Consequently, vibration of the workpiece can besuppressed. (It should be noted that since the number of chatteringvibrations differs at each machining position, the strength of thepushing force exerted by the supporting force generating unit may bechanged for each machining position.)

The machining assistance system may further include a memory for storingthe machining reaction force related data. The workpiece supportingforce control device may control the operation of the workpiecesupporting force generating unit and the operation of the supportingdevice based on the machining position related data and the machiningreaction force related data stored in the memory.

According to the above configuration, the machining reaction force foreach machining position is experimentally or theoretically estimated inadvance, and the workpiece supporting force can be controlled basedthereon. This makes it possible to eliminate the devices for detectingthe machining reaction force and simplify the machining assistancesystem. For example, in the case of experimentally estimating machiningreaction force for cutting work, cutting resistance may be measured by adynamometer in advance, and cutting reaction force estimated based onexperimental data may be stored.

The supporting device may be an articulated arm robot that retains theworkpiece supporting force generating unit by a hand, and the workpiecesupporting force control device may be configured to control operationof the articulated arm robot and the operation of the workpiecesupporting force generating unit.

The machining portion of a surface of the workpiece may be coated with afilm that increases rigidity of the workpiece and that is machinabletogether with the workpiece. In this case, the following pre-machiningtreatment may be performed: coating the machining portion of the surfaceof the workpiece with a film made of, for example, foamed resin orlow-melting alloy. According to the above configuration, the rigidity ofthe machining portion of the surface of the workpiece is increased, andthereby vibration during machining can be prevented.

Advantageous Effects of Invention

The present invention produces an advantageous effect of being able toprevent, in machining a low-rigidity workpiece, a reduction in machiningprecision due to deformation of the workpiece while suppressing areduction in production efficiency

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing the configuration of a machiningassistance system according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram showing the configuration of a workpiecesupporting force control device in the machining assistance system ofFIG. 1.

FIGS. 3A and 3B are schematic diagrams for describing workpiecesupporting force exerted by the machining assistance system of FIG. 1when side surface cutting is performed.

FIG. 4 is a block diagram showing the configuration of a machiningassistance system according to Embodiment 2 of the present invention.

FIG. 5 is a block diagram showing the configuration of the workpiecesupporting force control device in the machining assistance system ofFIG. 4.

FIG. 6 is a block diagram showing the configuration of a machiningassistance system according to Embodiment 3 of the present invention.

FIG. 7 is a block diagram showing the configuration of the workpiecesupporting force control device in the machining assistance system ofFIG. 6.

FIG. 8 is a block diagram showing the configuration of a machiningassistance system according to Variation 1 of Embodiment 3 of thepresent invention.

FIG. 9 is a block diagram showing the configuration of the workpiecesupporting force control device in the machining assistance system ofFIG. 8.

FIG. 10 is a block diagram showing the configuration of a machiningassistance system according to Embodiment 4 of the present invention.

FIG. 11 is a block diagram showing the configuration of the workpiecesupporting force control device in the machining assistance system ofFIG. 10.

FIG. 12 is a block diagram showing the configuration of a machiningassistance system according to Variation 2 of Embodiment 4 of thepresent invention.

FIG. 13 is a block diagram showing the configuration of the workpiecesupporting force control device in the machining assistance system ofFIG. 12.

FIGS. 14A and 14B are schematic diagrams for describing workpiecesupporting force exerted by a machining assistance system according toEmbodiment 5 of the present invention when milling is performed.

FIGS. 15A and 15B are schematic diagrams for describing workpiecesupporting force exerted by a machining assistance system according toEmbodiment 6 of the present invention when hole machining is performed.

FIG. 16 is a schematic diagram for describing workpiece supporting forceexerted by a machining assistance system according to Embodiment 7 whengrinding is performed.

FIGS. 17A and 17B are schematic diagrams for describing one example ofpre-machining treatment performed by a machining assistance systemaccording to Embodiment 8.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention are described withreference to the drawings. In the drawings, the same or correspondingelements are denoted by the same reference signs, and repeating the samedescriptions is avoided below. It should be noted that, variations ofthe embodiments described below are denoted by common serial numbers.

Embodiment 1

FIG. 1 is a block diagram showing the configuration of a machiningassistance system according to Embodiment 1 of the present invention. Asshown in FIG. 1, a machining assistance system 1 is a system forassisting a machining apparatus 2, which performs machining of aworkpiece W automatically.

First, the configuration of the machining apparatus 2 is described. Themachining apparatus 2 includes: a workpiece retaining tool 3, whichretains the workpiece W; a machining unit 4; and a machining controldevice 5. In the present embodiment, the machining apparatus 2 is, forexample, a machining center capable of performing different types ofmachining in accordance with the purpose of the machining, such as sidesurface cutting, front surface cutting, hole machining, and grinding.

The workpiece retaining tool 3 may be any tool, so long as it is capableof retaining the workpiece W. The workpiece retaining tool 3 includes,for example, a base and a mechanism that fixes the workpiece W on thebase. Although the workpiece W is not limited to a particular type ofworkpiece, the less the rigidity of the workpiece W is, the more thefunctional advantages of the present invention are exerted. Theworkpiece W, i.e., a machining target object in the present embodiment,is, for example, in the shape of a thin plate with low rigidity. Theworkpiece W may have a different shape, so long as the rigidity of theworkpiece W is low. For example, the workpiece W may be a thin-wallcylinder.

The machining unit 4 machines the workpiece W retained by the workpieceretaining tool 3 by driving a working tool 4 a. In the presentembodiment, the machining unit 4 is configured to cut a side surface ofthe workpiece W retained by the workpiece retaining tool 3 by causingthe columnar rotating cutting tool 4 a with cutting edges formed on itsperipheral surface to rotate about a central axis 4 c. A driver 4 d ofthe machining unit 4 includes, for example, a servomotor therein, anddrives the rotating cutting tool 4 a to rotate about the central axis 4c of a main shaft 4 b (i.e., the central axis of the rotating cuttingtool 4 a).

The machining control device 5 performs control of moving the machiningunit 4 relative to the workpiece retaining tool 3 to position theworking tool 4 a at a machining position. Specifically, the machiningcontrol device 5 includes: a moving mechanism (not shown) that moves themachining unit 4 relative to the workpiece retaining tool 3; and acontroller (not shown) that controls the movement of the machining unit4 relative to the workpiece retaining tool 3. In the present embodiment,the workpiece retaining tool 3 is fixed, and the machining unit 4 ismoved by the moving mechanism. The controller performs computernumerical control (CNC) to control the position of the machining unit 4by means of the moving mechanism and to control the operation of themachining unit 4, thereby controlling a cutting operation that therotating cutting tool 4 a performs on the workpiece W. The definition ofmachining position related data herein includes both data indicating themachining position and data correlated with the machining position.

Next, the configuration of the machining assistance system 1 isdescribed with reference to FIG. 1. The machining assistance system 1includes a workpiece supporting force generating unit 6, a supportingdevice 7, a dynamometer 9, and a workpiece supporting force controldevice 8.

The workpiece supporting force generating unit 6 generates workpiecesupporting force against machining reaction force that is exerted on amachining portion of the workpiece W by the working tool 4 a. In thepresent embodiment, the workpiece supporting force generating unit 6includes a columnar rotary body 6 a, a base 6 b, and a rotation driver 6d. The columnar rotary body 6 a is formed as an elastic body, forexample. The elasticity of the elastic body is suitably selected bytaking account of pushing force described below, the chatteringfrequency of the workpiece W, and so forth. In the present embodiment,the rotary body 6 a is a rubber roller. The rotary body 6 a includes arotary shaft (not shown) whose central axis is an axis 6 c. The rotaryshaft is rotatably retained by the base 6 b via bearings (not shown).The rotation driver 6 d is mounted to the base 6 b, and causes therotary body 6 a to rotate about the axis 6 c in accordance with arotational torque command from the workpiece supporting force controldevice 8. The rotation driver 6 d is configured, for example, as amotor, and the main shaft of the motor is coaxially connected to therotary shaft of the rotary body 6 a. In the present embodiment, themotor is a servomotor, for example.

The machining reaction force herein means force that is exerted from theworking tool to the workpiece at the time of machining In the case ofside surface cutting of the present embodiment, cutting resistance isexerted from the workpiece W to the working tool 4 a. In this case,reaction force against the cutting resistance, the reaction force beingexerted from the working tool 4 a to the workpiece W, is the machiningreaction force (cutting reaction force).

The supporting device 7 is not limited to a particular device, so longas the supporting device 7 moves the supporting force generating unit 6while supporting the supporting force generating unit 6. In the presentembodiment, the supporting device 7 is, for example, an articulated armrobot provided with a plurality of joint axes that are necessary for itsoperation. The articulated arm robot 7 retains the base 6 b of theworkpiece supporting force generating unit 6 by a hand 7 a provided atthe distal end of the arm.

The dynamometer 9 detects motive power exerted on the workpiece W. Inthe present embodiment, the dynamometer 9 is provided in such a manneras to support the base of the workpiece retaining tool 3 of themachining apparatus 2, and detects motive power (a load) exerted on theworkpiece W. The dynamometer 9 outputs the detected motive power to theworkpiece supporting force control device 8 as machining reaction forcerelated data. The definition of machining reaction force related dataincludes both data of machining reaction force and data correlated withthe machining reaction force. Since the motive power detected by thedynamometer 9 is the resultant force of machining reaction force exertedon the workpiece W and workpiece supporting force exerted on theworkpiece W by the supporting force generating unit 6, the motive powerdetected by the dynamometer 9 is data correlated with the machiningreaction force.

Based on the machining reaction force related data received from thedynamometer 9 and the machining position related data received from themachining control device 5, the workpiece supporting force controldevice 8 controls the operation of the workpiece supporting forcegenerating unit 6 and the operation of the supporting device 7, suchthat the workpiece supporting force generating unit 6 exerts workpiecesupporting force on the workpiece W against the machining reactionforce. In the present embodiment, the workpiece supporting force controldevice 8 is configured to control the operation of the articulated armrobot 7 and control the operation of the workpiece supporting forcegenerating unit 6. In addition, as described below, the workpiecesupporting force control device 8 is configured to: control theorientation and the position of the workpiece supporting forcegenerating unit 6, such that the rotary body 6 a exerts pushing force onthe workpiece W against cutting reaction force that is exerted on theworkpiece W by the rotating cutting tool 4 a; and control the operationof the rotation driver 6 d, such that the rotary body 6 a rotates andexerts a rotational torque on the workpiece W against a torque that isgenerated by the cutting reaction force.

FIG. 2 is a block diagram showing the configuration of the workpiecesupporting force control device (which may be hereinafter simplyreferred to as a supporting force control device) 8. As shown in FIG. 2,the workpiece supporting force control device 8 includes a memory 8 a, amotive power target value setter 8 b, an adder-subtracter 8 c, acompensator 8 d, a component force calculator 8 e, and a robotcontroller 8 f. The workpiece supporting force control device 8 isconfigured, for example, as an arithmetic operation device such as amicrocontroller or the like. The memory 8 a is configured, for example,as an internal memory of the microcontroller or the like. Theaforementioned blocks 8 b to 8 e are functional blocks that are realizedwhen the microcontroller executes a predetermined installed program.

The memory 8 a stores various data, such as a target value of the motivepower (hereinafter, referred to as a motive power target value).

The motive power target value setter 8 b retrieves the motive powertarget value stored in the memory 8 a, and outputs the retrieved motivepower target value to the adder-subtracter 8 c. In the presentembodiment, the motive power target value is set to zero, and when themotive power detected by the dynamometer 9 (hereinafter, referred to asa motive power detection value) is zero, it means that proper supportingforce is exerted on the workpiece W.

The adder-subtracter 8 c outputs a deviation of the motive power targetvalue from the motive power detection value (hereinafter, referred to asa motive power deviation), which is a value obtained by subtracting themotive power detection value from the motive power target value, to thecompensator 8 d.

The compensator 8 d performs, for example, PID compensation on themotive power deviation, and outputs the compensated motive powerdeviation to the component force calculator 8 e.

Based on the compensated motive power deviation, the component forcecalculator 8 e calculates pushing force that the rotary body 6 a exertsagainst cutting reaction force that is exerted on the workpiece W by therotating cutting tool 4 a, and calculates a rotational torque that therotary body 6 a exerts, by rotating, against a torque that is generatedby the cutting reaction force. It should be noted that the cuttingreaction force can be divided into: tangential-direction componentforce, which is exerted in the tangential direction of the rotatingcutting tool 4 a; perpendicular-direction component force, which isexerted perpendicularly to the tangential-direction component force; andaxial-direction component force, which is exerted in the direction ofthe rotational axis 4 c. The ratio among the tangential-directioncomponent force, the perpendicular-direction component force, and theaxial-direction component force can be estimated based on the manner ofperforming the cutting work, or can be detected by the dynamometer 9.Thus, the ratio is known. Based on the known ratio, the component forcecalculator 8 e calculates the pushing force and the rotational torque.In addition, the component force calculator Se outputs a command valueof the calculated pushing force to the robot controller 8 f, and outputsa command value of the calculated rotational torque to the rotationdriver 6 d.

The robot controller 8 f controls the operation of the articulated armrobot, which serves as the supporting device 7. In the presentembodiment, based on the machining position related data obtained fromthe machining control device 5, the robot controller 8 f outputs anoperation control signal to the articulated arm robot 7, such that thesupporting force generating unit 6 is positioned at a positioncorresponding to a machining position where the rotating cutting tool 4a performs machining. Specifically, for example, the robot controller 8f converts the machining position related data represented in acoordinate system of the machining apparatus 2 into data represented ina coordinate system of the articulated arm robot 7, and controls theoperation of the articulated arm robot 7 by using the converted data,such that the axis 6 c of the rotary body 6 a is parallel to therotational axis of the rotating cutting tool 4 a, and such that theposition of the rotary body 6 a in the height direction and the positionof the rotary body 6 a in the feed direction of the rotating cuttingtool 4 a correspond to the machining position where the rotating cuttingtool 4 a performs machining. Accordingly, the rotary body 6 a moves in amanner to follow the movement of the machining position where therotating cutting tool 4 a performs machining In addition, based on thepushing force command value, which is obtained from the component forcecalculator 8 e, the robot controller 8 f outputs an operation controlsignal to the articulated arm robot 7 to exert pushing force on theworkpiece W via the rotary body 6 a of the supporting force generatingunit 6. Specifically, in accordance with the pushing force commandvalue, the robot controller 8 f controls the operation of thearticulated arm robot 7 to change the position of the rotary body 6 aand the pushing force in the thickness direction of the workpiece W. Inthis manner, the pushing force based on the pushing force command valueis exerted on the workpiece W by the rotary body 6 a.

Meanwhile, the rotation driver 6 d controls the rotary body 6 a of thesupporting force generating unit 6 to exert a rotational torque on theworkpiece W based on the rotational torque command value obtained fromthe component force calculator 8 e. Specifically, the rotation driver 6d causes the rotary body 6 a to rotate in the same direction as therotation direction of the rotating cutting tool 4 a with a rotationaltorque corresponding to the rotational torque command value. In thismanner, the rotational torque corresponding to the rotational torquecommand value is exerted on the workpiece W by the rotary body 6 a.

Then, feedback control of the pushing force and the rotational torquethat are exerted by the rotary body 6 a is performed, such that themotive power detected by the dynamometer 9 is zero. As a result,workpiece supporting force that substantially matches the machiningreaction force exerted on the workpiece W is exerted on the machiningportion of the workpiece W, and thereby deformation of the workpiece dueto the machining reaction force is prevented. It should be noted that,by suitably selecting the elasticity of the rotary body 6 a, slightchattering vibration is absorbed by the rotary body 6 a and thussuppressed.

FIGS. 3A and 3B are schematic diagrams for describing workpiecesupporting force (which may be hereinafter simply referred to assupporting force) exerted by the machining assistance system 1 when sidesurface cutting is performed. A plan view of FIG. 3A and a perspectiveview of FIG. 3B only show the rotating cutting tool 4 a of the machiningunit 4, the workpiece W, and the rotary body 6 a of the supporting forcegenerating unit 6 for the sake of convenience of the description. Asshown in FIGS. 3A and 3B, in a case where the feed direction of therotating cutting tool 4 a is the direction toward the front side of thedrawing, the workpiece supporting force control device 8 uses thesupporting device (articulated arm robot) 7 to control the orientationand the position of the workpiece supporting force generating unit 6,such that: the axis 6 c of the rotary body 6 a is parallel to thecentral axis 4 c of the rotating cutting tool 4 a; the peripheralsurface of the rotary body 6 a faces the peripheral surface of therotating cutting tool 4 a with the workpiece W positioned in between;and the peripheral surface of the rotary body 6 a exerts pushing forceF′₂ on the workpiece W against perpendicular-direction component forceF₂ of the cutting reaction force that is exerted on the workpiece W bythe rotating cutting tool 4 a. In addition, the workpiece supportingforce control device 8 controls the operation of the rotation driver 6 dto cause the rotary body 6 a to rotate in a direction (indicated by acurved arrow in the drawing) that is the same as the rotation directionof the rotating cutting tool 4 a, such that a rotational torque F′₁ isexerted on the workpiece W against a torque that is generated bytangential-direction component force F₁ of the cutting reaction force.

Therefore, in a case where the machining apparatus 2 is an apparatus forperforming cutting of a side surface of the workpiece by means of therotating cutting tool 4 a as in Embodiment 1, the workpiece supportingforce is controlled to substantially match the machining reaction force,and thereby deformation of the workpiece W due to the machining reactionforce can be prevented even if the workpiece W is a low-rigidityworkpiece. Consequently, a reduction in machining precision duedeformation of the workpiece W can be prevented. Since it is notnecessary to, for example, reduce the machining conditions, a reductionin production efficiency can be suppressed.

Embodiment 2

Next, Embodiment 2 of the present invention is described. In thedescription below, the same components as those described in Embodiment1 are denoted by the same reference signs as those used in Embodiment 1,and the description of such common components is omitted. Hereinafter, adescription is given focusing on differences from Embodiment 1.

FIG. 4 is a block diagram showing the configuration of a machiningassistance system according to Embodiment 2. As shown in FIG. 4,Embodiment 2 is different from Embodiment 1 in that a machiningassistance system 1 a according to Embodiment 2 further includes acurrent sensor 10, which detects an electric current flowing through themotor of the driver 4 d of the machining unit 4, and the machiningreaction force related data is a current value of the electric currentflowing through the motor, which is detected by the current sensor 10.Here, the current value of the motor driving the rotating cutting tool 4a is a value corresponding to the machining reaction force.

FIG. 5 is a block diagram showing the configuration of the workpiecesupporting force control device 8 in the machining assistance system 1 aof FIG. 4. As shown in FIG. 5, in the present embodiment, the workpiecesupporting force control device 8 includes a machining reaction forcecalculator 8 g. The memory 8 a stores, as machining position relateddata, for example, data of the position of the rotary body 6 a, which istaught in advance. The robot controller 8 f retrieves the machiningposition related data taught in advance from the memory 8 a, and basedon the retrieved data, controls the operation of the articulated armrobot 7, such that the rotary body 6 a moves in a manner to follow themovement of the machining position where the rotating cutting tool 4 aperforms machining.

In the memory 8 a, for example, current values of the motor andmachining reaction force corresponding to each of the current values arestored as a table in advance. The machining reaction force calculator 8g receives a current value from the current sensor 10 as machiningreaction force related data, refers to the table, retrieves themachining reaction force that corresponds to the received current valuefrom the memory 8 a, and outputs the retrieved machining reaction forceto the component force calculator 8 e.

In this manner, feedforward control is performed, such that the pushingforce and the rotational torque exerted by the rotary body 6 acorrespond to the current value of the motor of the machining unit 4. Asa result, workpiece supporting force that substantially matches themachining reaction force exerted on the workpiece W is exerted on themachining portion of the workpiece W, and thereby deformation of theworkpiece due to the machining reaction force is prevented.

As described above, according to Embodiment 2, the machining reactionforce exerted on the workpiece W during the machining is indirectlydetected in real time by the current sensor 10. This makes it possibleto perform feedforward control of the workpiece supporting force byusing the motor current value detected by the current sensor 10.

Embodiment 3

Next, Embodiment 3 of the present invention is described. In thedescription below, the same components as those described in Embodiment1 are denoted by the same reference signs as those used in Embodiment 1,and the description of such common components is omitted. Hereinafter, adescription is given focusing on differences from Embodiment 1.

FIG. 6 is a block diagram showing the configuration of a machiningassistance system according to Embodiment 3 of the present invention. Asshown in FIG. 6, Embodiment 3 is different from Embodiment 1 in that amachining assistance system 1 b according to Embodiment 3 includes avibration meter 11 in place of the dynamometer 9 of Embodiment 1, thevibration meter 11 being provided on the base of the workpiece retainingtool 3 and measuring vibration of the workpiece W during machining, andthe machining reaction force related data is the vibration measured bythe vibration meter 11. Here, the vibration of the workpiece Wcorresponds to the machining reaction force exerted on the workpiece W.

FIG. 7 is a block diagram showing the configuration of the workpiecesupporting force control device in the machining assistance system 1 b.As shown in FIG. 7, in the present embodiment, the workpiece supportingforce control device 8 includes a vibration target value setter 8 h. Thevibration target value setter 8 h retrieves a vibration target valuestored in the memory 8 a, and outputs the retrieved vibration targetvalue to the adder-subtracter 8 c. In the present embodiment, thevibration target value is set to zero, and when the vibration measuredby the vibration meter 11 (hereinafter, referred to as a vibrationmeasurement value) is zero, it means that proper supporting force isexerted on the workpiece W. The adder-subtracter 8 c outputs a deviationof the vibration target value from the vibration measurement value(hereinafter, referred to as a vibration deviation), which is a valueobtained by subtracting the vibration measurement value from thevibration target value, to the compensator 8 d.

The compensator 8 d performs, for example, PID compensation on thevibration deviation, and outputs the compensated vibration deviation tothe component force calculator 8 e.

Based on the compensated vibration deviation, the component forcecalculator 8 e outputs a pushing force command value and a rotationaltorque command value. Since the operations thereafter are the same asthose described in Embodiment 1, the description thereof is omitted.

As described above, according to Embodiment 3, the machining reactionforce exerted on the workpiece W during the machining is indirectlymeasured in real time by the vibration meter 11. This makes it possibleto perform feedback control of the workpiece supporting force by usingthe vibration measured by the vibration meter 11. Consequently,vibration of the workpiece W can be suppressed.

[Variation 1]

FIG. 8 is a block diagram showing the configuration of a machiningassistance system according to Variation 1 of Embodiment 3 of thepresent invention. As shown in FIG. 8, the base 6 b of the rotationdriver 6 d is supported by an excitation device 12 for activelysuppressing vibration. A known excitation device can be used as theexcitation device 12. Since the structure of such an excitation deviceis well known, the description thereof is given below briefly. Theexcitation device 12 includes, for example, a movable body (not shown)elastically supported by a base (not shown) and an exciter (not shown)that causes the movable body to vibrate. The base 6 b of the rotationdriver 6 d is retained by the movable body, and the base of theexcitation device 12 is retained by the hand 7 a of the articulated armrobot 7. The excitation device 12 is configured to apply predeterminedvibration to the rotary body 6 a based on a vibration command from theworkpiece supporting force control unit 8. The excitation device 12 is,for example, an electromagnetic excitation device of a permanent magnettype.

FIG. 9 is a block diagram showing the configuration of the workpiecesupporting force control device in the machining assistance system ofFIG. 8. As shown in FIG. 9, in Variation 1, the workpiece supportingforce control device 8 further includes a vibration command valuecalculator 8 j. The vibration command value calculator 8 j calculates avibration command value based on the vibration measurement valuereceived from the vibration meter 11, and outputs the vibration commandvalue to the excitation device 12. In the present embodiment, thevibration command value calculator 8 j has, for example, a Fourieranalysis function, and calculates the frequency and amplitude of majorfrequency components from the received vibration measurement value, andgenerates and outputs such a vibration command value as to cancel themajor frequency components to the excitation device 12. In accordancewith the vibration command value, the excitation device 12 activelygenerates vibration that cancels the vibration of the vibrationmeasurement value. The generated vibration is superimposed on thepushing force via the rotary body 6 a, and is transmitted to theworkpiece W. This makes it possible to further increase the effect ofsuppressing the vibration of the workpiece W.

In general, the number of chattering vibrations occurring duringmachining differs at each machining position. Therefore, without usingthe excitation device 12, the strength of the pushing force exerted bythe supporting force generating unit 6 may be changed for each machiningposition. Alternatively, the pushing force exerted by the supportingforce generating unit 6 may be cyclically varied based on the naturalfrequency of the workpiece W. Further alternatively, the rotary body 6 amay be provided with a dynamic vibration absorber, and thecharacteristics of the dynamic vibration absorber may be changed inaccordance with the vibration.

Embodiment 4

Next, Embodiment 4 of the present invention is described. In thedescription below, the same components as those described in Embodiment1 are denoted by the same reference signs as those used in Embodiment 1,and the description of such common components is omitted. Hereinafter, adescription is given focusing on differences from Embodiment 1.

FIG. 10 is a block diagram showing the configuration of a machiningassistance system 1 c according to Embodiment 4. As shown in FIG. 10,the configuration according to Embodiment 4 is different from theabove-described configurations according to Embodiments 1 to 3 in thatthe machining assistance system 1 c according to Embodiment 4 does notinclude devices for detecting the machining reaction force, such as thedynamometer 9, the current sensor 10, and the vibration meter 11. Inaddition, the workpiece supporting force control device 8 according toEmbodiment 4 is different from the workpiece supporting force controldevice 8 according to Embodiment 1 in that the workpiece supportingforce control device 8 according to Embodiment 4 includes a memorytherein for storing machining reaction force related data in advance,and controls the operation of the workpiece supporting force generatingunit 6 and the operation of the supporting device 7 based on machiningposition related data received from the machining control device 2 andthe internally-stored machining reaction force related data.

FIG. 11 is a block diagram showing the configuration of the workpiecesupporting force control device 8 of FIG. 10. As shown in FIG. 11, inthe present embodiment, the workpiece supporting force control device 8includes: the memory 8 a, in which machining reaction force related datais stored in advance; and a machining reaction force command generator 8i. Based on machining position related data received from the machiningcontrol device 5, the machining reaction force command generator 8 iretrieves machining reaction force related data corresponding to each ofmachining positions from the memory 8 a, and outputs the retrievedmachining reaction force for each machining position to the componentforce calculator 8 e. Here, the memory 8 a stores the machining reactionforce for each machining position, and the stored machining reactionforce is experimentally or theoretically estimated in advance.

As described above, according to Embodiment 4, the machining reactionforce for each machining position is experimentally or theoreticallyestimated in advance, and the workpiece supporting force can becontrolled based thereon. This makes it possible to eliminate thedevices for detecting the machining reaction force and simplify themachining assistance system. For example, in the case of experimentallyestimating machining reaction force for cutting work, cutting resistancemay be measured by a dynamometer in advance, and cutting reaction forceestimated based on experimental data may be stored in the memory 8 a.

[Variation 2]

FIG. 12 is a block diagram showing the configuration of a machiningassistance system according to Variation 2 of Embodiment 4 of thepresent invention. As shown in FIG. 12, the machining assistance systemobtains machining position related data by a vision sensor 13 providedin the vicinity of the articulated arm of the robot 7.

FIG. 13 is a block diagram showing the configuration of the workpiecesupporting force control device in the machining assistance system ofFIG. 12. As shown in FIG. 13, in Variation 2, the workpiece supportingforce control device 8 includes: the memory 8 a, in which machiningreaction force related data is stored in advance; and the machiningreaction force command generator 8 i. Based on the machining positionrelated data received from the vision sensor 13, the machining reactionforce command generator 8 i retrieves machining reaction force relateddata corresponding to each of machining positions from the memory 8 a,and outputs the retrieved machining reaction force for each machiningposition to the component force calculator 8 e.

Embodiment 5

Next, Embodiment 5 of the present invention is described. In thedescription below, the same components as those described in Embodiment1 are denoted by the same reference signs as those used in Embodiment 1,and the description of such common components is omitted. Hereinafter, adescription is given focusing on differences from Embodiment 1.

FIGS. 14A and 14B are schematic diagrams for describing workpiecesupporting force exerted by a machining assistance system according toEmbodiment 5 of the present invention when milling is performed. Aperspective view of FIG. 14A and a side view of FIG. 14B only show themachining unit 4, the workpiece W, and the supporting force generatingunit 6 for the sake of convenience of the description.

As shown in FIGS. 14A and 14B, the machining unit 4 of the machiningassistance system according to Embodiment 5 is configured to performcutting (milling) of a surface of the workpiece W retained by theworkpiece retaining tool 3 (not shown) by causing the columnar rotatingcutting tool 4 a with cutting edges 40 formed on its distal end surfaceto rotate about the central axis 4 c.

The workpiece supporting force generating unit 6 includes: the columnarrotary body 6 a; and the rotation driver 6 d (not shown), which causesthe rotary body 6 a to rotate about the axis 6 c.

In Embodiment 5, in a case where the cutting feed direction of therotating cutting tool 4 a is the direction toward the front side of thedrawing, the workpiece supporting force control device 8 is configuredto use the supporting device 7 based on machining reaction force relateddata and machining position related data to control the orientation andthe position of the workpiece supporting force generating unit 6, suchthat: the central axis 6 c of the rotary body 6 a is parallel to thecentral axis 4 c of the rotating cutting tool 4 a; the distal endsurface of the rotary body 6 a faces the distal end surface of therotating cutting tool 4 a with the workpiece W positioned in between;and the distal end surface of the rotary body 6 a exerts pushing forceF′₂ on the workpiece W against perpendicular-direction component forceF₂ of cutting reaction force R that is exerted on the workpiece W by therotating cutting tool 4 a. In addition, the workpiece supporting forcecontrol device 8 is configured to control the operation of the rotationdriver 6 d to cause the rotary body 6 a to rotate in a direction reverseto the rotation direction of the rotating cutting tool 4 a, such that arotational torque F′₁ is exerted on the workpiece W against a torquethat is generated by tangential-direction component force F₁ of thegrinding reaction force R. In the present embodiment, control isperformed such that the axis 6 c of the rotary body 6 a is positionedcoaxially with the central axis 4 c of the rotating cutting tool 4 a.

Therefore, in the case where the machining apparatus is an apparatus forperforming milling of a surface of the workpiece by means of therotating cutting tool 4 a as in Embodiment 5, even if the workpiece W isa low-rigidity workpiece, a reduction in machining precision due todeformation of the workpiece W can be prevented while suppressing areduction in production efficiency.

Embodiment 6

Next, Embodiment 6 of the present invention is described. In thedescription below, the same components as those described in Embodiment5 are denoted by the same reference signs as those used in Embodiment 5,and the description of such common components is omitted. Hereinafter, adescription is given focusing on differences from Embodiment 5.

FIGS. 15A and 15B are schematic diagrams for describing workpiecesupporting force exerted by a machining assistance system according toEmbodiment 6 when hole machining is performed. A perspective view ofFIG. 15A and a side view of FIG. 15B only show the machining unit 4, theworkpiece W, and the supporting force generating unit 6 for the sake ofconvenience of the description. As shown in FIGS. 15A and 15B, themachining unit 4 of the machining assistance system according toEmbodiment 6 is configured to perform cutting (drilling) of a surface ofthe workpiece W retained by the workpiece retaining tool 3 (not shown)by causing the columnar rotating cutting tool 4 a with a drill bit 41formed on its distal end to rotate about the central axis 4 c.

Similar to Embodiment 5, the workpiece supporting force generating unit6 includes: the columnar rotary body 6 a; and the rotation driver 6 d(not shown), which causes the rotary body 6 a to rotate about the axis 6c.

In Embodiment 6, the workpiece supporting force control device 8 isconfigured to, based on machining reaction force related data andmachining position related data and by using the supporting device 7,control the orientation and the position of the workpiece supportingforce generating unit 6, such that: the central axis 6 c of the rotarybody 6 a is parallel to the central axis 4 c of the rotating cuttingtool 4 a; the distal end surface of the rotary body 6 a faces the drillbit surface of the drill bit 41 provided at the distal end of therotating cutting tool 4 a with the workpiece W positioned in between;and the distal end surface of the rotary body 6 a exerts pushing forceF′₂ on the workpiece W against perpendicular-direction component forceF₂ of cutting reaction force R that is exerted on the workpiece W by therotating cutting tool 4 a. In addition, the workpiece supporting forcecontrol device 8 is configured to control the operation of the rotationdriver 6 d to cause the rotary body 6 a to rotate in a direction reverseto the rotation direction of the rotating cutting tool 4 a, such that arotational torque F′₁ is exerted on the workpiece W against a torquethat is generated by tangential-direction component force F₁ of thecutting reaction force R. Also in the present embodiment, control isperformed such that the central axis 6 c of the rotary body 6 a ispositioned coaxially with the central axis 4 c of the rotating cuttingtool 4 a.

Therefore, in the case where the machining apparatus is an apparatus forperforming drilling of a surface of the workpiece by means of therotating cutting tool 4 a as in Embodiment 6, even if the workpiece W isa low-rigidity workpiece, a reduction in machining precision due todeformation of the workpiece can be prevented while suppressing areduction in production efficiency.

Embodiment 7

Next, Embodiment 7 of the present invention is described. In thedescription below, the same components as those described in Embodiment1 are denoted by the same reference signs as those used in Embodiment 1,and the description of such common components is omitted. Hereinafter, adescription is given focusing on differences from Embodiment 1.

FIG. 16 is a schematic diagram for describing workpiece supporting forceexerted by a machining assistance system according to Embodiment 7 whengrinding is performed. A plan view of FIG. 16 only shows the machiningunit 4, the workpiece W, and the supporting force generating unit 6 forthe sake of convenience of the description. As shown in FIG. 16, themachining unit 4 is configured to perform grinding of a side surface ofthe workpiece W retained by the workpiece retaining tool 3 (not shown)by causing a discoid rotating grinding tool 4 a with grinding stoneformed on its peripheral surface to rotate about the central axis 4 c.

The workpiece supporting force generating unit 6 includes: the columnarrotary body 6 a; and the rotation driver 6 d (not shown), which causesthe rotary body 6 a to rotate about the axis 6 c.

In a case where the grinding feed direction of the rotating cutting tool4 a is the direction toward the front side of the drawing, the workpiecesupporting force control device 8 is configured to control theorientation and the position of the workpiece supporting forcegenerating unit 6 by using the supporting device 7, such that: the axis6 c of the rotary body 6 a is parallel to the central axis 4 c of therotating grinding tool 4 a; and the rotary body 6 a exerts pushing forceF′₂ on the workpiece W against perpendicular-direction component forceF₂ of grinding reaction force that is exerted on the workpiece W by therotating grinding tool 4 a. In addition, the workpiece supporting forcecontrol device 8 is configured to control the operation of the rotationdriver 6 d to cause the rotary body 6 a to rotate in the same directionas the rotation direction of the rotating grinding stone 4 a, such thata rotational torque F′₁ is exerted on the workpiece W against a torquethat is generated by tangential-direction component force F₁ of thegrinding reaction force.

Therefore, in a case where the machining apparatus 2 is an apparatus forperforming grinding of a side surface of the workpiece W by means of therotating grinding stone 4 a as in Embodiment 7, even if the workpiece Wis a low-rigidity workpiece, a reduction in machining precision due todeformation of the workpiece W can be prevented while suppressing areduction in production efficiency.

Embodiment 8

Next, Embodiment 8 of the present invention is described. In thedescription below, the same components as those described in Embodiments1 to 7 are denoted by the same reference signs as those used inEmbodiments 1 to 7, and the description of such common components isomitted. Hereinafter, a description is given focusing on differencesfrom Embodiments 1 to 7. In Embodiments 1 to 7, the low-rigidityworkpiece W, e.g., a thin plate-shaped workpiece or a thin-wallcylindrical workpiece, is a machining target object. However, in thepresent embodiment, a machining portion of a surface of the workpiece Wis coated with a film that increases the rigidity of the workpiece W andthat is machinable together with the workpiece W. Accordingly,pre-machining treatment is performed to increase the rigidity of thesurface of the workpiece W. FIGS. 17A and 17B are schematic diagrams fordescribing one example of pre-machining treatment performed by amachining assistance system according to the present embodiment. Asshown in FIG. 17A, a machining assistance system ld includes a sprayingdevice 16 provided at the distal end of an articulated arm 15 of arobot. The spraying device 16 sprays mist-like foamed urethane resin 17out of its distal-end nozzle. As shown in FIG. 17B, by spraying thefoamed urethane resin 17 onto the workpiece W, a film made of the foamedurethane resin 17 is formed on the surface of the workpiece W. As aresult, the rigidity of the surface of the workpiece W is increased, andby machining the machining portion of the surface of the workpiece Wtogether with the foamed urethane resin 17, the vibration occurringduring the machining can be prevented. Alternatively, before performingthe machining, a low-melting alloy may be adhered to the periphery ofthe workpiece W to coat the machining portion of the surface of theworkpiece W with a film made of the low-melting alloy, and thereby therigidity of the workpiece W may be improved temporarily. In this case,treatment to melt the adhered alloy is performed after the machining.Further alternatively, the rigidity of the workpiece W may be increasedby coating the machining portion of the surface of the workpiece W witha thin clay film

Other Embodiments

As another embodiment, at least two of the following configurations maybe combined: a configuration where machining reaction force related datais detected by the dynamometer 9; a configuration where machiningreaction force related data is detected by the current sensor 10 of themotor; a configuration where machining reaction force related data ismeasured by the vibration meter 11; and a configuration where machiningreaction force related data is stored in the memory 8 a in advance.

Although it has been described that the machining apparatus 2 of each ofthe above embodiments is configured to move the working tool 4 a and fixthe workpiece W by the workpiece retaining tool 3, the configuration ofthe machining apparatus 2 is not thus limited. Alternatively, themachining apparatus 2 may be configured to fix the working tool and movethe workpiece W.

Although the supporting device 7 of each of the above embodiments isconfigured to move the workpiece supporting force generating unit 6while supporting the workpiece supporting force generating unit 6 by thehand 7 a provided at the distal end of the arm of the articulated armrobot 7, the supporting device may alternatively be configured as adedicated device that includes a support mechanism and a movingmechanism.

From the foregoing description, numerous modifications and otherembodiments of the present invention are obvious to a person skilled inthe art. Therefore, the foregoing description should be interpreted onlyas an example and is provided for the purpose of teaching the best modefor carrying out the present invention to a person skilled in the art.The structural and/or functional details may be substantially alteredwithout departing from the spirit of the present invention.

INDUSTRIAL APPLICABILITY

The present invention is applicable in machining a low-rigidityworkpiece.

REFERENCE SIGNS LIST

1, 1 b, 1 c, 1 d machining assistance system

2 machining apparatus

3 workpiece retaining tool

4 machining unit

5 machining control device

6 workpiece supporting force generating unit

7 supporting device

8 workpiece supporting force control device

9 dynamometer

10 current sensor

11 vibration meter

12 excitation device

13 vision sensor

15 robot arm

16 spraying device

17 foamed resin

W workpiece

1. A machining assistance system for assisting a machining apparatus,the machining apparatus including: a workpiece retaining tool thatretains a workpiece; a machining unit that machines the workpieceretained by the workpiece retaining tool by driving a working tool; anda machining control device that performs control of moving the machiningunit relative to the workpiece retaining tool to position the workingtool at a machining position, the machining assistance systemcomprising: a workpiece supporting force generating unit that generatesworkpiece supporting force against machining reaction force that isexerted on a machining portion of the workpiece by the working tool; asupporting device that moves the supporting force generating unit whilesupporting the supporting force generating unit; and a workpiecesupporting force control device that controls operation of the workpiecesupporting force generating unit and operation of the supporting devicebased on machining reaction force related data related to the machiningreaction force and machining position related data related to themachining position of the working tool, such that the workpiecesupporting force generating unit exerts the workpiece supporting forceon the workpiece against the machining reaction force.
 2. The machiningassistance system according to claim 1, wherein the machining unit isconfigured to perform machining of the workpiece retained by theworkpiece retaining tool by causing a columnar or discoid rotating toolwith a cutting edge or grinding stone formed on its peripheral surfaceor distal end surface to rotate about a central axis of the rotatingtool, the workpiece supporting force generating unit includes a columnarrotary body and a rotation driver that causes the rotary body to rotateabout a central axis of the rotary body, and the workpiece supportingforce control device is configured to, based on the machining reactionforce related data and the machining position related data and by usingthe supporting device, perform: control of an orientation and a positionof the workpiece supporting force generating unit, such that the centralaxis of the rotary body is parallel to the central axis of the rotatingtool, and the rotary body exerts pushing force on the workpiece againstcutting reaction force that is exerted on the workpiece by the rotatingtool; and control of operation of the rotation driver to cause therotary body to rotate, such that a rotational torque is exerted on theworkpiece against a torque that is generated by the cutting reactionforce.
 3. The machining assistance system according to claim 2, whereinthe machining unit is configured to perform cutting of a side surface ofthe workpiece retained by the workpiece retaining tool by causing acolumnar rotating cutting tool with a cutting edge formed on itsperipheral surface to rotate about a central axis of the rotatingcutting tool, and the workpiece supporting force control device isconfigured to, based on the machining reaction force related data andthe machining position related data and by using the supporting device,perform: control of the orientation and the position of the workpiecesupporting force generating unit, such that the central axis of therotary body is parallel to the central axis of the rotating cuttingtool, a peripheral surface of the rotary body faces the peripheralsurface of the rotating cutting tool with the workpiece positioned inbetween, and the peripheral surface of the rotary body exerts pushingforce on the workpiece against cutting reaction force that is exerted onthe workpiece by the rotating cutting tool; and control of operation ofthe rotation driver to cause the rotary body to rotate in the samedirection as a rotation direction of the rotating cutting tool, suchthat a rotational torque is exerted on the workpiece against a torquethat is generated by the cutting reaction force.
 4. The machiningassistance system according to claim 2, wherein the machining unit isconfigured to perform cutting of a surface of the workpiece retained bythe workpiece retaining tool by causing a columnar rotating cutting toolwith a cutting edge formed on its distal end surface to rotate about acentral axis of the rotating cutting tool, and the workpiece supportingforce control device is configured to, based on the machining reactionforce related data and the machining position related data and by usingthe supporting device, perform: control of the orientation and theposition of the workpiece supporting force generating unit, such thatthe central axis of the rotary body is parallel to the central axis ofthe rotating cutting tool, a distal end surface of the rotary body facesthe distal end surface of the rotating cutting tool with the workpiecepositioned in between, and the distal end surface of the rotary bodyexerts pushing force on the workpiece against cutting reaction forcethat is exerted on the workpiece by the rotating cutting tool; andcontrol of operation of the rotation driver to cause the rotary body torotate in a direction reverse to a rotation direction of the rotatingcutting tool, such that a rotational torque is exerted on the workpieceagainst a torque that is generated by the cutting reaction force.
 5. Themachining assistance system according to claim 2, wherein the machiningunit is configured to perform grinding of a side surface of theworkpiece retained by the workpiece retaining tool by causing a discoidrotating grinding tool with grinding stone formed on its peripheralsurface to rotate about a central axis of the rotating grinding tool,and the workpiece supporting force control device is configured to,based on the machining reaction force related data and the machiningposition related data and by using the supporting device, perform:control of the orientation and the position of the workpiece supportingforce generating unit, such that the central axis of the rotary body isparallel to the central axis of the rotating grinding tool, and therotary body exerts pushing force on the workpiece against grindingreaction force that is exerted on the workpiece by the rotating grindingtool; and control of operation of the rotation driver to cause therotary body to rotate, such that a rotational torque is exerted on theworkpiece against a torque that is generated by the grinding reactionforce.
 6. The machining assistance system according to claim 1, furthercomprising a dynamometer that detects motive power exerted on theworkpiece, wherein the machining reaction force related data is themotive power detected by the dynamometer.
 7. The machining assistancesystem according to claim 1, wherein the machining unit includes theworking tool and a motor that drives the working tool, the machiningassistance system further comprises a current sensor that detects anelectric current flowing through the motor, and the machining reactionforce related data is a current value of the electric current flowingthrough the motor, the electric current being detected by the currentsensor.
 8. The machining assistance system according to claim 1, furthercomprising a vibration meter that is provided on the workpiece retainingtool and that measures vibration of the workpiece retained by theworkpiece retaining tool, wherein the machining reaction force relateddata is the vibration measured by the vibration meter.
 9. The machiningassistance system according claim 1, further comprising a memory forstoring the machining reaction force related data, wherein the workpiecesupporting force control device controls the operation of the workpiecesupporting force generating unit and the operation of the supportingdevice based on the machining position related data and the machiningreaction force related data stored in the memory.
 10. The machiningassistance system according to claim 1, wherein the supporting device isan articulated arm robot that retains the workpiece supporting forcegenerating unit by a hand, and the workpiece supporting force controldevice is configured to control operation of the articulated arm robotand the operation of the workpiece supporting force generating unit. 11.The machining assistance system according to claim 1, wherein themachining portion of a surface of the workpiece is coated with a filmthat increases rigidity of the workpiece and that is machinable togetherwith the workpiece.